One of the regions in the field of MEMS (micro electro-mechanical systems) attracting attention includes bio-science, environment analysis and chemical synthesis. Devices referred to as microfluidic devices and μTAS (micro total analysis systems) are known as tools useful for such a region. A microfluidic device is prepared by forming a flow channel on a substrate of semiconductor, glass, ceramic or plastic materials and test samples, reagents or materials for chemical synthesis are made to flow through the flow channel of such a microfluidic device for the purpose of analysis or chemical synthesis. Development of devices that can exploit the advantages of microscale including a reduced consumption rate of solvent, sample and reagent and a high reaction speed if compared with conventional analysis techniques and batch processes and of apparatus/systems using such devices, is expected.
Japanese Patent Application Laid-Open No. 2004-340820 discloses a microfluidic device of a conventional type designed to employ an ultrasonic wave for transferring liquid and also for mixing/agitating liquid.
The microfluidic device disclosed in Japanese Patent Application Laid-Open No. 2004-340820 has a cross-sectional structure as illustrated in FIG. 6. Referring to FIG. 6, an ultrasonic platform type micro-chemical analysis system 100 includes a common platform 113 having a signal control circuit layer 111 and a transducer layer 112 and a transparent flow type microchip 114 arranged on the common platform 113. A flow channel 115 for transferring a sample or a reagent is formed in the inside of the flow type microchip 114 and ultrasonic transducers 116 are provided for the purpose of transferring and mixing/agitating a sample or a reagent in the flow channel 115. FIG. 6 is a cross-sectional view of a platform type micro-chemical analysis system 100 and hence ultrasonic transducers 116 seem to be arranged only one-dimensionally. However, ultrasonic transducers 116 are actually arranged in the form of a matrix. The ultrasonic transducers 116 arranged in the form of a matrix include liquid transferring transducers that are driven to operate along the flow channel 115 and mixing/agitation transducers that are arranged at a central part of the flow channel 115 in order to exploit their functional features.
However, the ultrasonic platform type micro-chemical analysis system disclosed in Japanese Patent Application Laid-Open No. 2004-340820 is accompanied by the following problems. Ultrasonic transducers 116 are arranged in the form of a matrix in the ultrasonic platform type micro-chemical analysis system according to Japanese Patent Application Laid-Open No. 2004-340820 and hence a large number of ultrasonic transducers 116 are required for the purpose of transferring and mixing/agitating liquid. Then, signals are applied to the ultrasonic transducers 116 for oscillations by means of respective signal generators and amplifiers. In other words, signal generators and amplifiers as many as the ultrasonic transducers 116 are required. Then, the apparatus/system for handling the platform type micro-chemical analysis system 100 is inevitably large and can involve high cost.
Additionally, the ultrasonic transducers 116 include liquid transferring transducers and mixing/agitation transducers that are different from each other. Thus, not only the apparatus/system can have large dimensions and involve high cost but also the platform type micro-chemical analysis system 100 per se can have large dimensions.